Stencil printing machine



Feb. 23, 1937. v c, ENGERT 2,071,824

STENCIL PRINTING MACHINE Filed Oct. 13, 1935 2 Sheets-Sheet 1 Filed Oct. 13, 1953 2 Shqets-Sheeb 2 Patented Feb. 23, 1937 UNITED STATES STENCIL PRINTING MACHINE Caspar Illinois F. Engert, Chicago, Ill., assignor to Poster Products, Inc., Chicago, 111.,

a corporation of Application October 13, 1933, Serial No. 693,424

13 Claims.

This invention relates, generally speaking, to an improved method of stencil printing and to a novel machine that is capable of performing the method. 7 In stencil printing, which is an old and well known process, pigment is forced through a flexible screen composed of bolting cloth, silk, copper mesh or the like, that is stretched tightly over a frame. In the beginning of the process, areas of the screen are rendered impervious and the remaining areas are left open to form the design to be printed. The cardboard or other material to be stenciled is placed beneath the stencil in close engagement, and paint is then poured upon the upper surface of the stencil. A rubber squeegee is next employed to spread the paint over the entire surface of the screen and force it through the open areas onto the work beneath, after which the stencil is raised and the printed sheet removed. 7

Until recently, practically all stencil printing was accomplished by hand operation and the output of the work and the quality thereof was entirely dependent upon' the skill and speed of the operator. Of comparatively recent date, some machines have entered the stencil printing fieldwhich, although expediting to an extent this kind of work, are subject to numerous objections. For example, they are comparatively 3o cumbersome and complicated, expensive to construct and operate, and get out of repair easily. Furthermore, one of the most outstanding of these employs a reciprocating action which, although faster than hand operation, is neces 35 sarily slower than is a machine such as one falling within the present invention, in which constant rotary motion in one direction is employed. I

The present invention therefore has for an 40 important object, the provision of an improved and simplified stencil printing machine which may be operated rapidly to produce uniformly good results.

An important feature of the present invention 45 that is conducive to the accomplishment of the recited object, resides in the provision of a pair of rotary cylinders between which the workis continually fed. One of these may take the form of a metal backing or base roll and the 50 other comprises a flexible screen stencil in cylindrical form. Pigment is admitted to the interior of the latter and. a stationary squeegee enclosed therein causes the pigment to be forced through the open areas in the screen and ap- 55 plied to the work in the desired figuration,

Another feature of the invention resides in the provision of a machine of this type in which the work is supplied from a continuous roll and is automatically stenciled and cut into sections after the stenciling operation has taken place. 5

Still another object of the invention residesin the employment of an improved method in the employment of which the stencil is disposed in a cylinder and is progressively moved over the work.

Other objects and features of the invention will become apparent from a reading of the following specification in the light of the accompanying drawings, in which,

Figure 1 is a view in front elevation, partially 15 in section, showing a stencil printing machine constructed in accordance with the present invention.

Figure 2 is a view in side elevation, taken along the line 2--2 of Fig. 1.

Figure 3 is a detailed view showing the manner of securing'the squeegee in place.

Figures 4 and 5 are detailed views illustrating the mariner of securing the cylindrical stencil to the members which support it, and

Figure 6 is a diagrammatic view illustrating the several operations performed by the machine.

As shown in Figs. 1 and 2 of the drawings, the stencil printing apparatus comprises an upper and lower roller or cylinder, the latter of which is driven from a pulley l0 and in turn drives the former through cooperating gears 12 and I4 located at opposite extremities of the rolls. The lower roll is in the form of a hollow metal drum I6 having a solid outer surface. It is journaled in bearings l8 carried by the frame 20 of the machine.

The upper roller, which is driven by the lower one, comprises a flexible screen stencil 22 having means positioned within it for forcing paint or pigment through the screen to be applied to work being fed between the rolls.

As illustrated, the fiexiblescreen 22, which may be made of any suitable material such, for example, as metal screen, bolting cloth, silk or the like, is secured in place in the following manner: The gear wheels l4, M are countersunk on their inner faces to receive anchoring rings 24 and 26 which are held in a fixed relation to the gear wheels by means of bolts 28. The gear wheel shown to the left ofthe machine, as viewed in -Fig'. 1, is journaled upon a bushing 30 and its hub is arranged to abut a thrust-bearing 32 .which is provided for a purpose that will hereinin section,

after be described. The gear wheel I 4 that is shown at the right of the machine as viewed in Fig. 1, is mounted for rotation on'a shaft 34 that extends lengthwise through the upper roller, forming its axis. This latter gear wheel is also provided with a thrust-bearing indicated by the reference numeral 36.

The shaft 34 which extends through the upper roller is secured to the frame 20 of the machine by means of supports 38 and normally remains stationary although it is so constructed as to permit a limited .amount of rotation for a purpose and in a manner that will be described later. The shaft supports not only theupper roller but it likewise carries the squeegee.

Referring to the latter, as shown in Figs. 1 and 2, a bracket comprising a plurality of arms 40, 40 and a bar 42 is carried by the shaft. The arms 40, 40 of the bracket encircle the shaft and are rigidly connected therewith. The bar 42, on the other hand, is permitted to rotate within the arms 40, 40 and has extending therefrom a plurality of supports 44, 44. The squeegee comprises a flexible resilient elongated strip 46, customarily rubber, that has its upper edge encased in a metal cap 48 and is secured therein by means of screws 50, as fully shown in Fig. l.

In order to removably secure the squeegee in a place within the upper roller, the lower ends of the supports 44, 44 are provided with open slots and the metal squeegee cap is provided with headed studs 52, 52, the shanks of which are small enough to extend through the slots and the heads of which are large enough to overlie the edges of the slots. In order to hold the squeegee in place after the studs have been inserted within the slots, the following arrangement is employed: As shown in Figs. 2 and 3, the supports 44, 44 are provided with rearwardly projecting portions 54, 54 having openings therein through which project headed studs 56, 56 similar to the studs 52, 52. A securing or locking strip 58 is provided and is formed with keyhole openings 60, 60. The enlarged openings in the keyhole slot receive the studs and by moving the strip lengthwise the small elongated openings move beneath the heads of the studs thereby locking the squeegee in place. In order to facilitate the lengthwise movement of the securing strip, a lever 62 is pivotally carried by a shelf or projection 63 which is formed integrally with a bell crank lever 82. A pin 65 projects from the strip and is arranged to be engaged by a cam surface formed on the lever 62. Thus, as the lever is moved from the dotted line position shown in Fig. 3 to the full line position, the pin is engaged and the strip moves lengthwise into locking engagement with the studs 56, 56.

Inasmuch as it will be desirable to vary the pressure applied to the squeegee in accordance with the viscosity of the pigments being used and likewise in accordance with the amount of fiow desired, the machine is provided with means for varying the amount of pressure thus applied. To this'end, as shown in Figs. 1 and 2, a stub shaft I0 is located within the main shaft 34 and is provided at its outer end with an arm I2 having an adjustable Weight I4 mounted thereon. The shaft 34 is provided with a slot I6 to permit the passage therethrough of a bolt I8, the lower extremity of which has screw-threaded engagement with the stub shaft I0 and the upper extremity of which is bifurcated to receive one extremity of a link 80. The opposite extremity of the link is pivotally connected to a bell crank lever 82 locking strip 0.

, II4, the upper that is mounted on the bar 42. In operation the weight applied to the arms 12 is transmitted through the stub shaft I0 to the bell crank lever 82 and thence is imparted to thev squeegee 46. By adjusting the position of the weight on the arm the desired amount of pressure may be imparted to the squeegee. weight is provided at its base with a bearing 84 which loosely encircles the shaft I0, and with a pin 86 that travels in an arcuate slot 88 formed in a collar 90. The weight, if moved downwardly, asshown in Fig. 2, causes the pin 86 to engage one end of the arcuate slot and transmits pressure to the squeegee. If the weight is swung upwardly, it passes the vertical position and .begins to descend downwardly to the left, as viewed in Fig. 2, until the pin engages the opposite end of the arcuate slot '88 whereupon the stub shaft is briefly rotated in the opposite direction to cause the pressure on the squeegee to be relieved. The extent of movement of the stub shaft "I0 is controlled by the length of the slot I6 in the shaft 34.

Inasmuch as it may be desirable from time to time, to change the location of the squeegee within the roller or drum, provision is made for rotating the main shaft 34 which rigidly carries the arms To this end, the shaft isprovided, adjacent to its left end, as viewed in Fig. 1, with a gear 92 fixed to the shaft, the gear being engaged by a worm 94 adapted to be rotated by a knurled finger' screw 96, as shown in Fig. 2. By means of this arrangement, the shaft 34 may be rotated to adjust the position of the squeegee within the drum or roller. In passing, it will be observed that the shaft 34 is hollow throughout its length and that the opening is enlarged near the center of the shaft at the point 98.

The pigment or paint may be admitted to the interior of the drum. in any desired manner, and as illustrated herein it enters through a flexible hose I00 which extends through the hollow shaft 34 and enters the interior of the drum through an opening I02 formed within the wall of the shaft. The pigment, or paint, is deposited by the hose in front of the squeegee, as shown in Fig. 2, and the latter member, during rotation of the drums, spreads the paint evenly over that portion of the drum having contact with the work and likewise forces the pigment through the perforations in the stencil screen and onto the work.

In connection with the. construction of the upper roller, there remains to be described the manner in which the flexible screen is fastened or anchored. As shown in Figs. 4 and 5, the side edges of the screen are secured to metal strips I04 which terminatein projecting tongues I06, I08. The peripheries of the anchoring rings 24 and 26 are recessed, as shown in Fig. 4 to receive the projecting tongues and likewise a securing or Seated within the anchoring ring 26 are two spring pressed plungers H2 and extremities of which project slightly above the recessed surface of the ring. The tongues I06 and I08 are formed with openings I I6 and I I8 for receiving the projecting portions of the plungers, and these openings are elongated to permit a limited amount of adjustment. To the end of holding the plunger extremities in locking engagement within the openings II6, I I8, the locking strip H0 is provided. The end of the strip overlies the plungers and the tongues holding them in cooperating relationship and the strip itself is temporarily latched in post- The arm I2 that carries the aonpaa tion by means of a stud bolt I20. A keyhole opening I22 is adapted to receive the head of the bolt and has a reduced portion for receiving the shank of the bolt, thereby locking the parts in place without the use of removable fasteners.

The ends of the screen 22 are extended slightly between the tongues and terminate in solid metal strips I24 and I26 (Fig. 5) which extend lengthwise of the roller or edges formed on their undersides to engage vertical walled recesses formed in the locking strip II 0 (which extends the length of the drum) to hold them in place and to maintain the screen in a taut cylindrical position. Studs I28 project upwardly at intervals from the locking strip H0 and have key and keyhole engagement with a securing or anchoring strip I30 which serves to prevent accidental displacement of the strips I24 and I26 from the recesses within the locking member 0.

The securing means at the left extremity of the cylinder, as viewed in Figs. 4 and 5, is identical with that located at the right end, which has just been described.

It will be appreciated that to remove or replace the screen 22 it will be necessary to decrease the distance between the anchoring rings 2d and 26 to enable the studs'I20, I20 to be disengaged from the reduced extremities of the keyhole openings I22, I22. To this end the bushing 30 is screwthreaded to the shaft 3A, as shown, and at its outer end is provided with recesses to be engaged by a wrench and with a locking collar 35. Rotation of the bushing 30 causes the gear wheel and anchoring ring at the left of the machine, as

viewed inFig. 1, to move slightly to the right to permit removal of the screen. Rotation in the reverse direction causes separation of the parts to clamp the screen in position, the thrust-bearings serving to force the parts apart without creating undue friction. Before leaving this topic, it might be pointed out that the locking strip H0 is provided with openings located above the plungers H2 and M4 to receive a tool for forcing the plungers into a retracted position, whereby the release of the tongues I06 and I08 is facilitated.

Referring to Figs. 2 and 6, the material M is supplied to the rolls from any suitable source and may, with expedition and efliciency, be fed from a roll R. The process is continuous since the rolls or drums are constantly rotatingin the same direction, and it is highly successful in the uniformity of results obtained since, as depicted in Fig. 6 for example, there is little more than a line contact between the two rolls, thereby reducing to a minimum the likelihood of error or smudges. An endless belt B moving at a faster rate of speed than the rolls to assure tautness. may be provided to convey the work from the stencilingstation to an automatic cutter which severs the work into sections of the desired length, after which the sections are carried away on a conveyor K. i

The method described herein permits the work to be fed in a continuous strip and stenciled, after which it is cut into sections. Such a process is to be contrasted with that now in vogue in which the sections are out in advance of the stenciling operation and each section must be separately and manually introduced into the stencil machine. In the present machine the entire operation is mechanical and substantially automatic.

Although only a single form of apparatus has been shown for carrying out the method, it is to drum and having depending be understood that numerous kinds of machines may be employed to the same end and that the invention is in nowise limited to the exact machine illustrated. Furthermore, it will be appreciated that certain changes in the design and construction of the machine shown may be made without departing from the scope of the invention as outlined in the appended claims.

.Having thus described my invention what I claim as new, and desire to secure by Letters Patent of the United States, is:

1. A machine of the character described, having, in combination, aplurality of rolls, one of said rolls comprising a backing roll and the other comprising a screen stencil, a plurality of supports for holding said stencil in a stretched condition,

means for moving the supports in the direction of one another to permit removal of the screen stencil, a squeegee positioned within the interior of the stencil, and meansfor admitting pigment to said stencil in advanceof the squeegee.

2. In a rotary stencil machine, a rotatable cylindrically formed stencil, means for securing the stencil in position comprising a plurality of supports for holding said stencil in stretched cylindrical condition, and means for moving the supports relatively toward each other to permit removal of the stencil.

3. In a rotary stencil machine, a rotatable stencil support, means for securing a stencil upon said support comprising a perforated tongue secured to the end of the stencil, and a depressible plunger mounted in said support and adapted on toiutward movement to engage within said perfora- 4. In a rotary stencil machine, a rotatable printing roll, and means for securing a stencil thereon comprising perforated tongues secured to the ends of said stencil, spring urged plungers adapted to be urged into the perforations in said tongues, and a locking strip overlying said tongues to limit the movement of said plungers.

5. In a rotary stenciling machine, a rotatable printing roll comprising a plurality of rotatable supports, means for securing a stencil thereon comprising perforated tongues secured to the ends of the stencil, depressible means within the supports adapted to engage within said perforations, a locking strip for limiting the movement of said depressible means, and means for moving the supports relatively toward each other to permit removal of said locking strip.

6. In a rotary stencil machine, a rotatable printing roll, means for securing a stencil thereon comprising shoulder members carried by the adj acent edges of said stencil, a locking strip having recesses within which the shoulder members are adapted to engage, and means for securing said f shoulder members in position within said recesses.

'7. In a rotary stenciling machine, a rotatable printing roll comprising a plurality of rotatable supports, means for securing a stencil thereon comprising perforated tongues secured to the ends of the stencil, depressible means within the supports adapted to engage within said perforations, a locking strip for limiting the movement of said depressible means, and recesses formed within said locking strip and shoulder members carried by and running substantially the length of the stencil adapted to engage within said recesses.

8. In a rotary stencil machine of the type having a rotatable stencil roll, a support within said roll, a squeegee, means for mounting said squeegee on said support comprising a member having a keyhole slot, and cam operated means for moving said member. I v

9. In a rotatable stenciling machine, a rotatable printing roll, a rotatable pressing roll cooperating therewith, means for feeding a strip between said rolls, and a conveyor for engaging the strip after it passes between the rolls, the paper-engaging surface of said conveyor having a lineal speed greater than the lineal speed of the paper-engaging surface of the printing and pressing rolls respectively.

10. In a rotatable stenciling machine, a rotatable printing roll, a rotatable pressing roll cooperating therewith, means for feeding a strip between said rolls, a conveyor for engaging the strip after it passes between the rolls, said conveyor means having a lineal speed greater than the lineal speed of the printing and pressing rolls, and a cutter mechanism for receiving the strip from said conveyor.

11. That improvement in methods of printing through fabric stencils, which comprises stretching a silk screen into a cylinder, rendering impervious certain areas of said silk screen, passing a fiat surface of the work into contact with said silk screen along a given line, forcing coloring matter through said silk screen on to said work along said line, and moving said work relative to said silk screen.

12. In a machine of the character described, a plurality of drums having peripheral engagement with one another, one of said drums being solid and another having a silk screen stencil surface, together with means located therein for forcing pigment through the perforations.

13. In a machine of the character described, a cylindrical roll comprising a silk screen stencil, means for holding said stencil in a stretched condition, and means for forcing pigment through the perforations in said stencil.

CASPAR F. ENGERT. 

